Faceplate mounting structure for cathode ray tube color selection electrode

ABSTRACT

This disclosure depicts a color cathode ray tube including a color selection electrode and a suspension device for suspending the electrode adjacent the faceplate of the tube. The disclosure is particularly directed to a low-cost, compact stud comprising part of the suspension device. The novel stud is relatively flat with a cross-section of substanially greater width than thickness. The stud has a forward portion, at least a tip of which having provision for coupling the stud to the color selection electrode.

United States Patent [1 1 Palac June 17, 1975 1 FACEPLATE MOUNTINGSTRUCTURE FOR CATHODE RAY TUBE COLOR SELECTION ELECTRODE [75] Inventor:

[73] Assignee: Zenith Radio Corporation, Chicago,

Ill.

[22] Filed: Dec. 26, 1973 [21] App]. No.: 428,176

Kazimir Palac, Carpentersville, Ill.

[52 u.s.c1 ..313/40s;313/404 51 Int. c1... HOlj 29/02; HOlj 29/08; 110131/20 581 Field ofSearch ..3l3/855, 92 B, 64,402,

[56] References Cited UNITED STATES PATENTS 11/1960 Fyler 313/92 B X10/1961 Godfrey 313/92 B X 3,497,746 2/1970 Duistermaat et al. 313/85 S3,700,949 10/1972 Watanabe et al 313/85 S 3,735,179 5/1973 Kaplan 313/92B Primary Examiner-Robert Segal Attorney, Agent, or Firm-John H. Coult 57] ABSTRACT This disclosure depicts a color cathode ray tube including acolor selection electrode and a suspension device for suspending theelectrode adjacent the faceplate of the tube. The disclosure isparticularly directed to a low-cost, compact stud comprising part of thesuspension device. The novel stud is relatively flat with across-section of substanially greater width than thickness. The stud hasa forward portion, at least a tip of which having provision for couplingthe stud to the color selection electrode.

4 Claims, 12 Drawing Figures SHEET 4 3 i3 7 \7 4 0 3 6 00 II 000 0 00 00 00 oo o 000 o oo o 0 0000 2 oo 0 OO oo oo oo o 00 0000 o 0000 o 000 000 PATENTEUJuHWtsvs 3, 99 525 SHEET 3 rllllll/ QIA'IIIIA FACEPLATEMOUNTING STRUCTURE FOR CATHODE RAY TUBE COLOR SELECTION ELECTRODE CROSSREFERENCE TO RELATED APPLICATIONS This application is related to but inno way dependent upon copending applications Ser. No. 395,334, filedSept. 7, 1973; Ser. No. 424,017, filed Dec. 12, 1973; and Ser. No.285,985, filed Sept. 5, 1972, all assigned to the assignee of thepresent invention.

BACKGROUND OF THE INVENTION This invention relates generally to colorcathode ray tubes of the type having a color selection electrode, andmore particularly to a suspension device for suspending a colorselection electrode in a color tube. The invention is especiallyconcerned with an improved stud comprising part of such an electrodesuspension device.

It is well known and widely practiced to secure electrode-supportingstuds on a color tube envelope by embedding the studs directly in theenvelope while the envelope is in a plastic state. Conventional studs ofthe type adapted to be embedded by a hot sealing operation aremanufactured by heading, deep drawing and- /or machining operations andthus are relatively expensive. Further, they occupy a relatively largearea on the stud-receiving surface. The latter drawback is notsignificant in tubes of the type having a front panel with a flangewhich receives the studs. This invention, however, while having generalapplicability, is most advantageously applied to a novel color tubehaving a flangeless faceplate. In this novel color tube, the colorselection electrode is preferably supported by studs secured directly tothe inner surface of the faceplate on which is deposited the phosphorscreen. Thus, since the studs and associated suspension structure occupya part of the faceplate screen area, it is extremely important that theamount of area occupied be minimized. Conventional studs of the typeadapted to be embedded would occupy an undesirably great amount of thefaceplate inner surface area.

OBJECTS OF THE INVENTION It is a general object of this invention toprovide an improved device for suspending a color selection electrode ina color cathode ray tube.

It is a more particular object of this invention to provide an improvedelectrode suspension device which includes a low-cost, compact studadapted to be embedded in the color tube envelope.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the invention whichare believed to be novel are set forth with particularity in theappended claims. The invention, together with further objects andadvantages thereof, may best be understood, however, by reference to thefollowing description taken in conjunction with the accompanyingdrawings, and in which:

FIG. 1 is a fragmentary perspective view of a corner of a color cathoderay tube, showing a color selection electrode for the tube and asuspension device for suspending the electrode adjacent a faceplate ofthe tube;

FIG. 2 is an exploded view of the electrode suspension deviceillustrated in FIG. 1;

FIG. 3 is an enlarged, sectioned elevational view of the electrodesuspension device shown in FIGS. 1 and FIG. 4 is a perspective view of acolor cathode ray tube faceplate, showing four novel studs comprisingpart of the electrode suspension device shown in FIGS. l-3;

FIG. 5 is an enlarged view showing one of the electrode-supporting studsembedded in a cathode ray tube faceplate;

FIG. 6 is a sectional view taken along lines 6-6 in FIG. 5;

FIG. 7 is a perspective view, somewhat schematic and partially exploded,of a fixture for embedding the studs shown in FIGS. 1-5 in a cathode raytube faceplate;

FIG. 8 is an enlarged fragmentary view of a studholding chuck comprisingpart of the FIG. 7 fixture;

FIG. 9 is a sectional view taken along lines 99 in FIG. 8;

FIG. 10 isa sectional view taken along lines 10--l0 in FIG. 8;

FIG. 11 is a'view of a color tube faceplate showing studs according tothis invention embedded therein, the studs having a differentconfiguration and being positioned in a different geometry than as shownin FIG. 4; and

FIG. 12 is an enlarged fragmentary view showing one of the studsillustrated in FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention is directed toproviding an improved device for suspending a generally rectangularcolor selection electrode on the envelope of a rectangular-type colorcathode ray tube. The suspension device of this invention may be used tosuspend a color selection electrode in color cathode ray tubes ingeneral which are of the type requiring such an electrode, however it isespecially useful for suspending upon the envelope of a color tube anovel, lightweight, flexible shadow mask as described and claimed in thereferent copending applications Ser. Nos. 285,985 and 395,334. Thesuspension devices are spaced around the electrode to define asuspension system; in a preferred embodiment, the system includes foursuspension devices, one at each comer of the electrode. The lightweight,flexible mask alluded to above is adapted to be supported at its cornersso as to permit it to conform to the contour of a cathode ray tubefaceplate adjacent which it is mounted and to have an exact and precisespacing from the faceplate (commonly known as the Q spacing). This maskis described and claimed, per se, in the above-noted copendingapplications Ser. No. 285,985 and 395,334.

FIGS. 1-3 illustrate a portion of a color cathode ray tube 8incorporating a system of suspension devices according to thisinvention, one of which is shown at 10, for suspending a color selectionelectrode, illustrated as taking the form of a shadow mask 11. The tube8 is depicted as having an envelope with a novel construction comprisinga funnel 12 sealed to a generally rectangular, flangeless faceplate 14.

The mask 11 is illustrated as being of a low-cost, lightweight,frameless, flexible character, being preferably formed integrally from asingle sheet of electrically conductive material such as steel, all asdescribed in detail and claimed in the referent copending applicationSer. No. 395,344. The mask 11 is illustrated as having a curved centralportion 18 which has formed therein a pattern of electron-transmissiveapertures 20. The mask 11 includes a stiffening channel 22 surroundingand joined with the central portion 18.

The mask 11 has a skirt 24 of generally constant depth surrounding andjoined with the channel 22. The skirt 24 includes a forwardly directed,outwardly flared body portion terminating in a leading edge portion 28.As described in detail in the referent copending application, theconfiguration of the strengthening channel 22 and of the skirt 24 issuch as to enhance the stiffness of the mask and to shield, to themaximum degree possible, the phosphor screen on the inner surface of thefaceplate 14 from stray or overscanned electrons emanating from electronguns (not shown) in the neck of the tube 8.

This invention is concerned with the provision of a compact, low-costsuspension device for cornersuspending a color selection electrode, suchas a shadow mask 11, adjacent the faceplate portion of a cathode raytube. The devices represent an improvement on devices described andclaimed in the referent copending application Ser. No. 424,017. The masksuspension devices 10 according to this invention each comprise a stud34 of novel construction, discussed in detail hereinafter, which isembedded (by an operation to be described) at a precise location in thetube envelope.

Each suspension device 10 includes electrodemounted means forretentively engaging the stud 34. In the illustrated preferredembodiment, the electrodemounted means is shown as comprising a rigidbracket 40 externally surrounding and embracing a corner of the mask 11.The bracket 40 is secured at opposite ends 42, 44 to adjoining sides ofthe mask 11. The electrode-mounted means further includes coupling meanssupported by the bracket 40 which comprises a discrete spring 45 and alug 46 (to be described) for engaging a lug-receiving opening 47 in thestud 34.

In the illustrated preferred embodiment, the bracket 40 comprises twoedge-bonded strips of metal which have different coefficients of thermalexpansion. The bracket 40 deflects, upon heating of the mask 11, tocause the mask 11 to move nearer to the faceplate 14 so as to provideQ-compensation. By selecting strip materials to have a predetermineddifference in coefficient of thermal expansion, and by selecting anappropriate length for the bracket arms 48, 50, a predeterminedtemperature increase in the electrode will produce an appropriatetranslation of the mask 11 to effect Q-compensation. That is to say, themask 11 will be translated nearer to the faceplate 14 a distanceeffective to maintain registration between the electron beam landingsand the phosphor elements constituting the phosphor screen.

In accordance with one aspect of this invention, the spring 45preferably has a reverse bend defining a first leg 58 which is securedto the bracket 40 and an opposed second leg 60 which carries the lug 46.The leg 58 is bifurcated into two parts 62, 64 which straddle alug-passing opening 66 in thebracket 40. As shown with particularclarity in FIGS. 2 and 3, the lug 46 is secured to leg 60 and extendsfrom the out-facing side thereof through the lug-passing opening 66 inthe bracket 40 for retentive engagement with the lugreceiving opening 47in the stud 34 when the mask 11 is operatively mounted in the tube 8.

The suspension device 10, by the novel construction above-described, hasthe following desirable proper ties. First, the suspension device isextremely compact, owing in large part to the use of the reverse-bentspring 45 which arches inwardly from the bracket 40 and which deflectsin the unused space above the flared skirt 24 on the mask 11. Second,the spring 45 is protected against possible damage during handling ofthe mask. Third, by the disclosed arrangement wherein only thespring-biased lug 46 extends beyond the bracket, the suspension deviceis highly suited to an automated or semi-automated mask mountingoperation. Fourth, by the use of a rigid bracket 40 to which is securedspring 45, economies in the fabrication of the suspension device areachieved, since the bracket 40 can be welded to the mask 11 in a lowtolerance attachment operation and the spring 45 subsequently attachedprecisely to the bracket by a higher tolerance attachment operation. Thelatter attachment operation (welding for example) is much easier to holdtolerances on than the operation in which the bracket 40 is secured tothe mask 11.

To enhance the engagement/disengagement characteristics of the lug 46and the stud 34, the lug-receiving opening 47 maybe circular, as shown,or may be generally triangular in shape with rounded corners such thatthe lug 46 makes a three-point engagement with the opening 47. Furtherto this end, the lug 46 preferably has at least two sections ofdifferent taper, the taper increasing toward the distal end of the lug46. In the illustrated preferred embodiment, two sections 68, 70 ofincreasing taper are shown.

As discussed above, due to the need for an extremely compact suspensiondevice when corner mounting is employed, it is desirable that the spring45, which functions in part to permit disengagement of the lug 46 fromthe stud 34, require a minimum travel in order to effect the saiddisengagement. Further, it is necessary in order to preclude excessivevibration of the mask 11 during operation of the tube, and in order toresist excessive mechanical shocks during handling of the tube (whichmay reach 40 Gs or more), that the suspension devices 10 each exert apredetermined firm loading force on the mask, e.g., in the order of 2.0pounds. It is desirable, however, that any loading spring employed notbe so stiff as to overload the mask when the tube is baked duringassembly or when the tube is operating at maximum operatingtemperatures. It is also desirable that any such loading spring apply apredetermined load to the mask which is relatively constant within arelatively broad tolerance range.

With these objectives and difficulties considered, the spring 45 has theafore-described reverse bent, inwardly arched construction and ispreferably prestressed such that the leg 60 exerts a predetermined loadon the bracket 40 when the device is not suspending the mask; this loadis substantially equal to the desired load imposed on the mask by thespring 45 when the mask is mounted in the tube. Second, prestressing ofthe spring 45 permits the use of a relatively low rate I spring. The useof a low rate spring which is prestressed has the result that the loadwhich is applied to the mask when mounted in a tube, can be,predetermined with lower required tolerances since the associatedforce-versus-displacement characteristic thereof is re]- ativelyshallow. The lower tolerances associated with the relatively low ratespring also imply that the loading of the mask 11 is more constant overa wider range of spring deflections than would be the case if arelatively stiff spring were employed. The lower tolerances permitted bythe use of a relatively low rate spring also result in economies inmanufacture of the device 32.

This invention is especially directed to the provision of a low-cost,compact stud, as shown at 34, which is adapted to be embedded in thetube envelope by a hot sealing operation. FIG. 4 shows four of the novelstuds 34 embedded in the faceplate 14 on the diagonals of the faceplateand oriented perpendicular thereto. FIG. 5 is a close-up elevationalview of one of the studs 34 showing in detail the structure of thepreferred form of the stud 34. The stud 34, according to this invention,is relatively flat with a cross-section of substantially greater width wthan thickness t. The stud 34 is preferably a stamping formed in astamping operation from sheet metal stock such as 430 titanium stainlesssteel, or nickel-steel.

The stud 34 has a forward portion 72 at least a tip of which is adaptedto be embedded in the faceplate 14, and a rearward portion 74 whichcontains the lugreceiving opening 47. The opening 47 receives the lug 46mounted on the distal end of spring 45. In the illustrated embodiment,the forward portion 72 is wider than the rearward portion 74. Thetransition from the forward portion 72 to the rearward portion 74comprises a pair of abrupt shoulders 76, 78. The shoulders 76, 78facilitate the embedding of the studs in the faceplate 14, as willbecome evident hereinafter.

In order to strengthen the stud 34, if necessary, the stud cross-sectionmay be caused to have a transverse curvature. In the illustratedembodiment, shown with particular clarity in FIGS. 5 and 6, the stud 34includes a lengthwise corrugation 80 which is formed integrally thereinduring the stud stamping operation.

FIG. 7 schematically depicts a fixture 81 for embedding the studs 34 inthe faceplate 14. The FIG. 7 apparatus is illustrated as including abase 82 from which projects three carbon-tipped support rods 84, 86, 88for supporting the faceplate 14. Three alignment posts 90, 92, 94 serveto align the faceplate 14. A pair of clamping assemblies 96, 98 includespring-biased, carbon-tipped pistons 100, 102 which urge the faceplateagainst the alignment posts 9094. The fixture 81 is illustrated asincluding a platen 104 which supports four substantially identicalchuck-burner assemblies 106, 108, 110, 112. The platen 104 is raised andlowered by means of air cylinders, shown schematically at 114, 116, 118and 120.

Each of the chuck-burner assemblies 106-l 12 is illustrated ascomprising a slide bar 131 which is adjustable along the faceplatediagonal by means of a slot 122 in the platen 104 and a pair of threadedbolts 124, 126. Each of the chuck-burner assemblies 106112 supports onthe outermost end thereof a chuck 130, shown with particular clarity inFIGS. 810. The chuck 130 includes a cavity 132 having a configurationcorresponding to that of the stud 34 to be chucked, and a gas manifoldcomprising a gas passageway 134 leading to an annular combustion chamber136 surrounding the cavity 132. A gas hose 138 is coupled to thepassageway 134 to conduct gas to the combustion chamber 136. The platen104 is shown elevated above its normal base 82 and associatedstructures.

In operation, to embed four studs 34 in the faceplate 14, the studs areloaded into the chucks 130 and secured (by means not shown). The gas isignited in the combustion chamber 136 and the studs are preheated. Theplaten 104 is then lowered by means of the air cylinders 114-120 intoproximity with the faceplate 14 to cause the faceplate 14 to be heatedlocally until plastic in the regions where the studs 34 are to beembedded. As the platen is lowered, the platen 104 engages the alignmentposts -94, thus assuring alignment thereof with respect to the faceplate14.

When the faceplate 14 has been heated sufficiently, the platen 104 islowered until the chucks engage the upper surface of the faceplate 14.The chucks 130 thus serve, not only to hold the studs 34 and to act asburners for heating the studs and the faceplate, but also act as depthgauges to precisely predetermine the degree of penetration of the studs34 into the faceplate 14.

After the studs have been embedded, the burners are shut off and theseal is permitted to cool. When the seal has become sufficiently rigidto support the studs, the platen 104 is withdrawn.

FIGS. 1-10 describe a suspension system in which the studs 34 arelocated on the diagonals of the faceplate 14 and oriented perpendicularthereto. The novel stud structure of this invention may be employed inother suspension systems for example, suspension systems wherein thestuds are located in the vicinity of the corners but oriented parallelto the sides of the faceplate 14', as shown in FIG. 11, with thelongitudinal axis 142 of the studs aligned parallel to the axis of thetube. In such a system each stud 140 is embedded in the faceplate 14' ata predetermined angle 0 with respect to the stud-receiving surface ofthe faceplate, the angle 0 being measured in the plane of the stud (seeFIG. 12).

In accordance with an aspect of this invention, a tip edge 144 of theforward portion 146 of a stud 140 is angled with respect to thelongitudinal axis 142 of the stud 140 such that when the stud isembedded, the tip edge 144 is substantially parallel to an adjacentportion of the stud-receiving surface 148 of the faceplate. By thusangling the tip edge 144, uniform penetration of the faceplate isachieved. The FIGS. 11-12 stud 140 is different from the FIGS. 1-10 studin other respects also. The stud 140 is illustrated as having straightsides, rather than having shoulders as shown at 76, 78 on the stud 34.No corrugation or cross-sectional curvature is included, such beingunnecessary if the sheet stock employed is sufficiently rigid. In apreferred embodiment successfully tested, the stud was preferably formedof 0.080 nickel-steel stock and was roughly 0.375 inch wide by 0.50 inchlong. No corrugation or crosssectional curvature was needed or provided.

The invention is not limited to the particular details of constructionof the embodiments depicted and other modifications and applications arecontemplated. For example, whereas the suspension device illustrated hasbeen shown as having a particular construction, the novel studprinciples depicted can be employed in accordance with this invention toprovide studs having other configurations and studs useful in othertypes of suspension devices. Whereas the FIG. 7 stud embedding apparatusis shown as employing burners for heating the studs, it is a well-knownalternative to use RF heating coils to superheat the studs prior toembedment in a cathode ray tube envelope. The FIG. 7 fixture is intendedto be schematic only; the particular apparatus and method employed forembedding the studs, per se, constitute no part of this invention.Rather than embedding the studs in a cooled panel by the use of analignment fixture, as described, the studs may be embedded in thefaceplate during the faceplate molding operation. Other changes may bemade in the abovedescribed apparatus without departing from the truespirit and scope of the invention herein involved, and it is intendedthat the subject matter in the above depiction shall be interpreted asillustrative and not in a limiting sense.

I claim:

1. A component of a color cathode ray tube ofa type having a colorselection electrode which carries electrode suspension elements at aplurality of points spaced around the periphery thereof, comprising:

a flangeless, three-dimensionally curved faceplate having a concaveinner surface and a plurality of low-cost, lightweight metal studsembedded at spaced points around the periphery of said faceplatecorresponding to the locations of the electrode suspension elements onthe color selection electrode for supporting a color selection electrodein precise spaced relationship to said faceplate inner surface, each ofsaid studs being relatively flat with a cross-section of substantiallygreater width than thickness and having a tip embedded in the envelopeand means for making captive engagement with a suspension element on acolor selection electrode.

.-2. The apparatus defined by claim 1 wherein said stud is a stampingformed from sheet metal stock.

3. For use in a rectangular-type color cathode ray tube, a system forsuspending a generally rectangular color selection electrode on theenvelope of the tube at a predetermined precise spacing from a faceplateportion of the envelope, including four electrode suspension devicesspaced around the electrode, one at each corner thereof, each devicecomprising:

a low-cost, lightweight stud embedded in the tube envelope, said studbeing relatively flat with a crosssection of substantially greater widththan thickness, said stud having a forward portion, at least a tip ofwhich is adapted to be embedded in the envelope, and a rearward portionincluding coupling "means for coupling the stud to a color selectionelectrode; and

electrode-mounted means mounted at a corner of the electrode, includingspring means and means carried by said spring means for making captiveengagement with said coupling means on said stud.

4. The apparatus defined by claim 3 wherein said stud is a stampingformed from sheet metal stock.

1. A component of a color cathode ray tube of a type having a colorselection electrode which carries electrode suspension elements at aplurality of points spaced around the periphery thereof, comprising: aflangeless, three-dimensionally curved faceplate having a concave innersurface and a plurality of low-cost, lightweight metal studs embedded atspaced points around the periphery of said faceplate corresponding tothe locations of the electrode suspension elements on the colorselection electrode for supporting a color selection electrode inprecise spaced relationship to said faceplate inner surface, each ofsaid studs being relatively flat with a cross-section of substantiallygreater width than thickness and having a tip embedded in the envelopeand means for making captive engagement with a suspension element on acolor selection electrode.
 2. The apparatus defined by claim 1 whereinsaid stud is a stamping formed from sheet metal stock.
 3. For use in arectangular-type color cathode ray tube, a system for suspending agenerally rectangular color selection electrode on the envelope of thetube at a predetermined precise spacing from a faceplate portion of theenvelope, including four electrode suspension devices spaced around theelectrode, one at each corner thereof, each device comprising: alow-cost, lightweight stud embedded in the tube envelope, said studbeing relatively flat with a cross-section of substantially greaterwidth than thickness, said stud having a forward portion, at least a tipof which is adapted to be embedded in the envelope, and a rearwardportion including coupling means for coupling the stud to a colorselection electrode; and electrode-mounted means mounted at a corner ofthe electrode, including spring means and means carried by said springmeans for making captive engagement with said coupling means on saidstud.
 4. The apparatus deFined by claim 3 wherein said stud is astamping formed from sheet metal stock.